1. Field of the Invention
The present invention relates to a clearance-free supporting structure for a pivotal axle (portion), for example, the clearance-free supporting structure of the pivotal axle (portion) disposed within a shift lock mechanism (or a shift lock unit) in an operation device of a multi-stage automatic transmission to be mounted in an automotive vehicle.
2. Description of the Related Art
A Japanese Patent Application First Publication No. 2003-127691 published on May 8, 2003 (which corresponds to a United States Patent Application Publication No. US 2003/0074999 A1 published on Apr. 24, 2003) exemplifies a previously proposed shift lock mechanism for a multi-stage automatic transmission. In the multi-stage automatic transmission disclosed in the above-described Japanese Patent Application First Publication, functions of a park lock at a P (Parking) position and an R (Reverse) inhibit at an N (Neutral) position are provided. In the above-described Japanese Patent Application First Publication, the shift lock mechanism which achieves both of the above-described functions is integrated into a single unit and fixed on an outer side surface of a frame of the multi-stage automatic transmission.
In details, a lock unit is fixed onto the outer side surface of the frame. The lock unit is provided with a lock lever which is brought in close contact with a stop (or stopper) lever attached to a select lever. Lock unit includes a base plate on which a plurality of engagement portions are engaged with a plurality of engagement holes opened to one of side surfaces of left and right (lateral) directions of the frame and to which the lock lever, a pivotal axle portion, and an actuator such as a solenoid to pivot the pivotal axle portion are operably attached. The lock lever and its pivotal axle portion are constructed as follows: The pivotal axle portion orthogonal to a vicinity to a pivotal axle base portion of a main body of the lock lever in an approximately sector shape and having a predetermined length are integrally formed of a synthetic resin. The pivotal axle portion is provided with a small-diameter axle portion fitted into an axle supporting portion formed on a base plate. This small-diameter axle portion can be fitted into a cut-out (notch) portion. The axle supporting portion other than the notch portion is an arc-shaped projection rotatably supporting the pivotal axle portion. One end portion of the pivotal axle portion is rotatably supported on an axle supporting portion constituted by an annular projection insertably formed on base plate. The other end portion of pivotable axle portion is integrally formed with a lower portion projected toward an oblique side direction and integrally formed with a lever portion projected in parallel to an axial center line of the pivotal axle portion and at a position having a predetermined length toward a radial direction from the axial center line. Hence, the pivotal axle portion is pivotable and can be moved toward the axial direction via the axle supporting portions. Hence, a clearance against a window hole of the frame with which lock lever is engaged can be absorbed. The lever portion is formed with an elongated hole. A pin projection installed on an operation portion of the actuator is engaged with the elongated hole. The pin projection is elongated so that a distance between the operation portion and lever portion is so long that the clearance between inner side surfaces of the window hole can be absorbed. A release lever is pivotally supported on the base plate by means of an axle and is biased by means of a spring so that its one end portion of the release lever and the projection are always spaced apart from each other. The other end portion of the release lever is brought in close contact with a lever end portion of a pin whose upper end portion is exposed to an indicator portion.